Conventional devices such as microprocessors and graphics processors that are used in high-performance digital systems may have varying current demands based on the processing workload. For example, current demands may increase dramatically when a block of logic is restarted after a stall or when a new request initiates a large computation such as the generation of a new image. Conversely, current demands may decrease dramatically when a block of logic becomes idle. When the current demand increases and sufficient power or energy is not available, the supply voltage that is provided to the device may drop below a critical voltage level, potentially causing the device to fail to function properly. When the current demand decreases and the supply voltage that is provided to the device rises above a critical voltage level, circuits within the device may fail to function properly and may even be destroyed.
A conventional switching regulator is an electric power conversion device that interfaces between a power supply and a device, providing current to the device and responding to changes in current demands to maintain a supply voltage level. Conventional voltage regulators used for central processing units (CPUs) and graphics processing units (GPUs) convert 12 Volts to approximately 1 Volt using a “buck” converter. Switches of the buck converter are typically controlled with proportional integral derivative (PID) technique to modulate a pulse width during which a high-side switch is coupled to the 12 Volt power supply to provide current to the device. While a conventional buck converter is simple to operate and requires only a few components (i.e., two switches, a filter capacitor, and an inductor), a conventional buck converter controlled using the PID technique may take longer than desired to respond to current demand transients of the device, resulting in a drop in supply voltage, so that the supply voltage that is provided to the device may drops below the critical voltage level.
FIG. 1 illustrates voltage and current waveforms 100 showing a conventional buck converter controlled using the PID technique, in accordance with the prior art. A first waveform corresponds to the current iL in the inductor of the converter. A second waveform corresponds to the voltage vC at the filter capacitor. A third waveform corresponds to the width of the pulse ta during which the high-side switch is enabled. A PID controller responds to load current transients of +5 Amps at 100 μs and −3 Amps at 400 μs by increasing or decreasing ta, respectively. As FIG. 1 shows, the PID controller takes about five 10 μs cycles to pump up current in the inductor and then additional cycles are required to raise the voltage vC on the filter capacitor. The peak drop of vC is 90 mV 30 μs after the transient. The response time of the PID controller should be reduced to better regulate the voltage level vC.
Thus, there is a need for improving regulation of voltage levels and/or other issues associated with the prior art.